184 TWENTIETH REPORT ON THE STATE CABINET. 



Fiff. 26. 



Rastrites barrandi. 



The species for whicli I have proposed tlie name Thamnograptus consist 

 of slender cylindrical stipes and branches, some of them very similar in 

 general aspect to Rastuites; but the alternating branches are long and 

 slender, and we have found no appearance of cellules on any part of tlie 

 specimens known. 



In the accompanying illustration, the branchlets are given oif alternately 

 on the opposite sides of a stipe or rachis, and the slender 'solid axis can 

 be traced from the main stipe into and along tlie centre of the branchlets. 

 The analogy between these forms "and the celluliferous graptolites of the 

 preceding illustrations does not appear to be very intimate, but they occur 

 in the same beds, and the fossil has the same texture and substance. 



Fig. 26. 



Thamnograptus typus. 



* It seems to me not improbable that these bodies are related to Rastrites ; and when we 

 come to know the character of the entire frond of the latter genus, greater analogy will be 

 found than now appears to exist. 



